Apparatus for and method of expanding earth materials



Jdl zz, 1969 W. '7

APPARATUS FOR AND METHOD OF EXPANDING EARTH MATERIALS :F'iled Sept. 1, 1967 2 Sheets-Sheet 1 INVENTOR JOSEPH JOHN BROUK co-hmPwwz ATTORNEYS 2 Sheets-Sheet 2 llll I. Y E

.u R PUP llllllllllllllllllllllllllllllllllllllll l o :i|||lllklmlmmunhflmflwlllllllilili T INVENTOR JOSEPH JOHN BROUK J. J. BROUK APPARATUS FOR AND METHOD OF EXPANDING EARTH MATERIALS Filed Sept. 1, 1967 United States Patent U.S. Cl. 26321 20 Claims ABSTRACT OF THE DISCLOSURE An apparatus for expanding earth material such as perlite, including a kiln constructed of a plurality of concentric tubes. A first feed means introduces earth material for preheating to a longitduinal feed passage formed between adjacent tubes at a first entrance spaced longitudinally from the input end of the kiln. The second feed means introduces the earth material for lesser preheating to a feed passage ata second entrance spaced longitudinally from the first entrance. The longitudinal feed passages are located at different radial distances from the burner flame and the earth material may be transferred between passages.

The method of expanding earth material comprises thesteps of passing one or more supplies of earth material longitudinally of an elongate kiln selectively at one or more predetermined radial distances from and in heat exchange relation to the burner flame, transporting each supply of earth material at any one of a plurality of predetermined longitudinal distance to the input end of the kiln, preheating each supply of earth material at any one of a plurality of preheat temperatures and delivering the preheated earth material directly into the burner flame for expansion in the kiln.

BACKGROUND OF THE INVENTION This invention relates generally to improvements in an elongate expander kiln adapted to expand earth materials such as perlite, vermiculite and other expansible ores, and more particularly to apparatus for subjecting such earth materials to dilferent preheat temperatures from burner flame and to different conditions of preheat most suitable for each specific earth material. Provision is made for preheating a plurality of earth materials simultaneously under different temperatures and conditions of preheat to obtain a mix that is expanded by the burner flame and discharged from the kiln as a premixed product.

The invention also relates generally to a method of expanding such earth materials by preheating each supply of earth material at any one of a plurality of preheat temperatures from the burner flame depending on the selected radial distance from the flame at which each earth material supply is passed in heat exchange relation to the flame in traveling to the input kiln end, and depending on the selected longitudinal distance of such travel.

In heretofore conventional types of expanding or putfing kilns, such as that shown in U. S. Patent No. 2,721,069, there is no provision of any apparatus for preheating the ore by utilizing the heat of the primary burner flame. The furnaces in US. Patent Nos. 2,602,782 and 2,807,453

disclose a separate preheat chamber isolated physically out of thermal exchange relation to the expander kiln. These kilns are adapted to expand only one ore at a time, and do not have any apparatus for introducing different ores simultaneously in the same kiln.

Other types of kilns are adapted for the expansion of a mixture of ores, such as perlite and vermiculite, in the same kiln, as suggested in U. S. Patent No. 3,010,911. However, there is no apparatus for providing different degrees of preheat for the diflferent ores, and certainly; there is no provision that such different preheat tempera tures and conditions of preheat can be provided by the primary burner flame and the expander kiln structure.

SUMMARY OF THE INVENTION The apparatus for expanding earth material includes means into a feed passage at a first entrance spaced longitudinally from the input kiln end. In moving through the feed. passage to the input kiln end, the earth material is preheated from the primary burner flame. A second feed means introduces and delivers earth material to the input kiln end at a different temperature from that delivered by the first feed means. The earth materials are then collect-i ed and delivered directly into the burner flame for expansion in the kiln.

A second entrance at which the second feed means introduces earth material to a feed passage is spaced longi tudinally from the first entrance in a direction toward the input kiln end, whereby the earth material incurs a lesser preheat in traveling a shorter distance through its associated feed passage than the earth material introduced by the first feed means. In one usage of the apparatus, the

second feed means can introduce e'arthmaterial directly to the input kiln end without preheat flame.

each feed passage is subjected to a greater preheat temperature than the next radially outward feed passage.

When the first feed means introduces earth material intoone feed passage, and the second feed means introduces earth material into another feed passage, the earth materials are subjected to different preheat temperatures.

A bypass means is disposed between an adjacent pair of tubes to divert earth materials selectively from one feed passage to another feed passage located at a-ditferent radial distance from the burner flame to change the pre-j heat temperature to which the earth material is subjected.

The method of expanding earth material comprises the' steps of moving earth material a predetermined distance longitudinally of an elongate kiln and in heat exchange relation to the primary burner flame, preheatingthe earth Patented July 22, 1969 from the burner Because a longitudinal feed passage is provided be- .tween each adjacent pair of tubes comprising the kiln,

determined radial distance from the burner flame .and

is selectively moved radially outward to a dilferent radial distance from the burner flame, yet in heat exchange relation to the burner flame, at which radial distance the earth material is moved longitudinally of the kiln. The earth material is preheated by the burner flame during such longitudinal transportation at the greater radial distance at a lesser preheat temperature than that subjected to the earth material moved longitudinally at the lesser radial distance.

The second earth material is moved a shorter predetermined distance than the first earth material, and the second earth material is moved longitudinally of the kiln and in heat exchange relation to the burner flame. The second earth material is preheated with the same burner flame during such longitudinal movement. The preheated first and second earth materials are collected and delivered, together, direcly into the burner flame for expan- The method includes the step of moving the first and second earth materials selectively at different radial distances from the burner flame to attain different preheat temperatures. One of the earth materials can be selectively diverted from one radial distance to a different radial distance to change the preheat temperature subjected to such earth material.

Briefly, the method includes the steps of passing one or more supplies of earth material longitudinally of the elongate kiln selectively at one or more predetermined radial distances and in heat relation to the burner flame, moving each supply of earth material at any one of a plurality of predetermined longitudinal distances to the input kiln end, and preheating each supply of earth material at any one of a plurality of preheat temperatures from the burner flame depending upon the radial and longitudinal distances.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of the expander kiln;

FIG. 2 is an enlarged, fragmentary cross-sectional view taken on line 2-2 of FIG. 1;

FIG. 3 is an enlarged, cross-sectional view taken on line 33 of FIG. 1;

FIG. 4 is an enlarged, cross-sectional view taken on line 44 of FIG. 1;

FIG. 5 is an enlarged, cross-sectional view taken on line 5-5 of FIG. 1; and

FIG. 6 is an enlarged, fragmentary cross-sectional view of the kiln at the input end taken on line 6-6 of FIG. 1.

Referring now by characters of reference to the drawings, and first to FIG. 1, the furnace assembly includes a substantially horizontal platform generally indicated by 10 supported by a plurality of concrete pedestals referred to by 11. A substantially horizontal, rotary kiln 12 is mounted on and supported by the platform 10.

The kiln 12 is constructed of three substantially concentric tubes 13, 14 and 15 disposed substantially horizontal and in radially spaced relation. The tubes 13, 14 and 15 provide an input kiln end 16. For reasons which will later appear upon detailed description of parts, the intermediate tube 14 extends beyond the other end of the outer tube 15, and the inner tube 13 extends still further beyond the intermediate tube 14. This extended portion of inner tube 13 constitutes the output end 17 of the kiln 12.

As is best seen in FIG. 6, each adjacent pair of tubes is provided with a longitudinal feed passage therebetween. For example, the inner tube 13 and the intermediate tube 14 are radially spaced to provide a first feed passage 20. The intermediate tube 14 and the outer tube 15 are radially spaced to provide a second feed passage 21. It will be understood that the feed passages 20 and 21 are located at different radial distances from the longitudinal axis of the kiln 12. The feed passages 20 and 21 open circumferentially to the input kiln end 16,

The rotary mounting and drive for the kiln 12 is shown in FIG. 1. A pair of longitudinally spaced gears 22 and 23 are fixed to the outer tube 15, one such tube gear being located near each end of the kiln 12. A coacting drive gear 24 is journaled between pillow blocks 25, the drive gear 24 meshing with the tube gear 22. A similar idler gear 26 is journaled between a pair of pillow blocks 27, the idler gear 26 meshing with the tube gear 23. The gears 24 and 26 support the kiln 12 in a substantially horizontal position.

The power means for rotating the substantially horizontal kiln 12 includes an electric motor 30 operatively connected to an output shaft 31 of a gear reduction until 32. The output shaft 31 is operatively connected to the drive gear 24 through a belt and pulley connection 33. Upon energization of motor 30, the drive gear 24, meshing with the tube gear 22, turns the kiln 12 at a predetermined speed.

A first feed means includes a scoop boot 34 operatively associated with the intermediate tube 14. The construction of the scoop boot 34 is best shown in FIG. 3. The scoop boot 34 includes a circular housing 35 defining a chamber 36. Extending outwardly from and rotatable with the intermediate tube 14 are a pair of scoop blades 37 that wipe the interior of housing 35 and direct earth material contained in the chamber 35 through entrance ports 40 and into the first passage 20. The earth material is fed into the scoop boot 34 through a feed tube 41, constituting a part of a vibrator shaker, leading from the lower end of a hopper 42. After delivery of the earth material from the scoop boot 34 into the inner feed passage 20 through the entrance ports 40, the earth material is fed longitudinally along the feed passage 20 by conveyor flights 43 toward the input kiln end 16.

At the input end 16 of kiln 12, lifter ring, referred to by 44, is carried by and rotatable with the outer tube 15. The lifter ring 44 includes a circular housing 45 in which are mounted a plurality of circumferentially spaced lifter blades 46 extending into the chamber 47 defined by housing 45. As the earth material is fed from the passages 20 and 21 into the input kiln end 16, the earth material is moved into the lifter ring 45. The lifter blades 46 collect the earth material and raise it to an elevation at which the earth material drops fromt he blades 46.

A burner 50 is located at the input kiln end 16 and is supported by a column 51. The burner 50 includes a burner tunnel 52 extending into the center of lifter ring 44 and arranged along the longitudinal axis of kiln 12. The burner 50 is fed by forced air from blower 53 and by gas through conduit 54, the air and gas being mixed in valve 55 and the mixture fed into the burner 50. The burner 50 directs a forced air flame 56 into the input kiln end 16 and into the inner tube 13, the burner flame 56 extending substantially the length of the kiln 12 along its longitudinal axis.

When earth material is dropped from the lifter blades 46, the earth material falls directly into the burner flame 56. The burner flame 56 heats the earth material, expands it and blows the resultant expanded product longitudinally through the inner tube 13 toward the output kiln end 17. Attached to the interior of inner tube 13 adjacent input kiln end 16, are a plurality of circumferentially spaced, secondary lifter blades 57. Any earth material that is not immediately expanded by the burner flame 56 is blown into the inner tube 13, where it is again collected and lifted by the secondary blades 57, and dropped again into the burner flame 56 for expansion. The expanded material is blown toward the output kiln end 17 by the forced air flame 56 and is fed in this direction by the internal conveyor flight 60 formed on the interior wall of inner tube 13.

Located at the output kiln end 17 is a collecting end chamber 61 into which the expanded earth material is directed from the inner tube 13. The expanded earth material falls from the end chamber 61 through a discharge tube 62 into a collecting pit (not shown) or on a floor (not shown) where the earth material can be scooped up and stored. An exhaust tube 63 extends upwardly from the. end chamber 61 for exhausting burnt gases.

A bypass means generally indicated by 64 in FIG. 1 is best shown in FIG. 2. This bypass means 64 is located on kiln 12 and is spaced longitudinally from the scoop boot 34 in a direction toward the input kiln end 16. As is shown in FIG. 2, the bypass means 64 includes a bypass plate 65 that is adapted to close selectively either bypass port 66 formed in the intermediate tube 14 or the opening 67 formed in the outer tube 15. The bypass plate 65 is supported by a pair of adjustable bolts 70 threadedly connected to and carried by a plate 71 that is attached to the outer tube 15 by brackets 72.

When the bypass plate 65 selectively closes the bypass port 66, as shown in broken lines in FIG. 2, the earth material moving from the first entrance ports 40 along the feed passage 20 will continue in its path along such feed passage 20 as the earth material passes over the bypass plate 65. However, when the bypass plate 65 is selectively lowered to the position shown in full lines in FIG. 2, the bypass port 66 is open. Therefore, the earth material will fall through the bypass port 66 from the feed passage 20 and into the radially outward feed passage 21. The earth material will then move along the feed passage 21 to the input kiln end' 16.

The earth material, such as perlite, is fed into the feed passage 20 through the first entrance port 40, and in moving longitudinally the length of the kiln 12 to the input kiln end 16, the earth material is subjected to a preheat temperature from the primary burner flame 56. Thus, such earth material is preheated from the burner flame 56 and is conditioned for most efficient expansion when dropped directly into the burner flame 56 by the lifter ring 44. Under some circumstances, it is desirable to subject the earth material fed into the first entrance ports 40 by scoop boot 34 to a slightly less preheat temperature. In this event, the bypass plate 65 is lowered from the broken line position to the full line position as shown in FIG. 2, so that the earth material will be diverted from feed passage 20 through the bypass port 66 and into the radially outward feed passage 21. During the passage of the earth material through the feed passage 21, such earth material is subjected to a lesser preheat temperature than it would be subjected to during movement through the radially inward feed passage 20.

A second feed means is provided for feeding earth material into the kiln 12. This second feed means includes a scoop boot 73 associated with the outer tube 15 in longitudinally spaced relation to the scoop boot 34 in a direction toward the input kiln end 16. From FIG. 4, it will be seen that the scoop boot 73 includes a substantially circular housing 74 forming a chamber 75. Attached to and rotatable with the outer tube 15 are a pair of scoop blades 76 adapted to wipe the interior of housing 74 and direct the earth material in chamber 75 through second entrance ports 77 and into the feed passage 21. Another hopper 80 carries the earth material, such as perlite or vermiculite, and feeds such material through a feed tube 81, constituting a part of a vibrator shaker into the housing 74.

At times it is most desirable, in order to obtain most effective and eflicient expansion of a particular earth material such as vermiculite, to subject such earth material to a lesser preheat from the burner flame 56 than would be possible by its introduction through the scoop boot 34. Under these circumstances, such earth material is fed into the scoop boot 73 and into the feed passage 21 through the second entrance ports 77. The earth material is then pushed longitudinally through the feed passage 21 in a direction toward the input kiln end 16 by a conveyor flight 82. Because the second entrance ports 77 are located much closer to the input kiln end 16 than the first entrance ports 40, the earth material travels a shorter distance and consequently is subjected to a lesser preheat from the burner flame 56.

At times, it is convenient and advantageous to utilize both feed means simultaneously. In this event, the earth material fed from the scoop boot 34 travels along the feed passage 20, while the earth material fed from the scoop boot 73 travels along the radially outward feed passage 21. Both earth materials are preheated during such movement by the burner flame 56, the earth material moving from the scoop boot 73 along the feed passage 21 and having a lesser preheat than the earth material traveling from the scoop boot 34 through the radially inward feed passage 20. The preheated earth materials are discharged from the feed passages 20 and 21 into the input kiln end 16, where the mixture is collected and elevated by the lifter blades 46 of the lifter ring 44, and subsequently dropped directly into the burner flame 56 for expansion in the kiln.

Of course, it will be understood that in the above examples of usage, the bypass means 64 can be utilized if desired. When the bypass means 64 is utilized, the earth material is diverted from the passage 20 into the radially outward passage 21 where it is preheated by the burner flame 56 in the same manner but at a lesser temperature, and is mixed with the earth material fed into the second passage 21 by the scoop boot 73.

A third feed means can be used to introduce earth material directly into the input kiln end 16 without preheating, it such is desirable to obtain most eflective expansion of the earth material in the kiln. This feed means includes a hopper 83 for holding the earth material. The earth material is fed from the hopper 83 directly into the lifter ring 44 through a feed tube 84, as provided by a Syntron shaker. Of course, the earth material is not preheated by the burner flame 56 in the kiln, but is immediately collected and raised by the lifter blades 46, and dropped directly into the burner flame 56 for expansion within the kiln. The third feed means can be used individually or in combination with any one of the other two feed means previously described.

It is thought that the functional advantages of the substantially horizontal, rotary kiln 12 have become fully apparent from the foregoing detailed description of parts, but for completeness of disclosure, the operation will be briefly described.

First, it will be understood that any one of the feed means can beused individually. For example, the earth material from hopper 42 is fed through the feed tube 41 into the scoop boot 34. The scoop blades 37 direct such earth material through the first entrance ports 40 into the feed passage 20. As the earth material moves longitudinally along the feed passage 20 toward the input kiln end 16, the earth material is preheated by the primary burner flame 56. If a lesser preheat is desired, the bypass means 64 can be.utilized to divert all or a portion of the earth material from the feed passage 20 into the radially outward feed passage 21 where it is subjected to a lesser preheatfThe earth material is collected at the input kiln end 16 and elevated by the lifter blades 46 and dropped directly into the burner flame 56. The burner flame 56 heats the earth -material, expands it and blows it longitudinally along the inner tube 13 toward the output kiln end 17. The expanded earth material is caught in the end chamber 61 and deposited for storage through the discharge tube 62.

The earth material held in hopper is fed into the scoop boot 73 through the feed tube 81. The scoop blades 76 introduce the earth material through the second entrance ports 77 into the feed passage 21. In moving through the feed passage 21 from the second entrance ports 77 toward the input kiln end 16, the earth material is preheated by the primary burner flame 56. Obviously, because the earth material is moving a shorter distance through a radially outward feed passage 21, the earth material has a lesser preheat than the earth material fed through the scoop boot 34. Of course, the earth material is deposited into the input kiln end 16 and is fed directly into the burner flame 56 by lifter ring 44 in the same manner. The expansion and collection of the earth material has been previously described.

Earth material held in the hopper 83 is fed directly into the lifter chamber 47 through the feed tube 84 without being subjected to any preheat from the burner flame 56. The lifter ring 44 delivers this earth material directly into the burner flame 56 for expansion.

The earth material held within any one of the hoppers 42, 80 or 83 can be mixed with the earth material of any one or all of the other earth materials contained in the other hoppers. For example, while earth material is fed through passage 21 from the scoop boot 34, earth material can be introduced into passage 20 through the scoop boot 73 simultaneously. The preheated earth materials are fed into the input kiln end 16 from passages 20 and 21, and the mixture is fed directly into the burner flame 56 by the lifter ring 44. As discussed previously, a portion or all of the feed material from scoop boot 34 can be diverted by bypass means 64 selectively into the radially outward passage 21 where it is mixed and preheated with the earth material fed into passage 21 by the longitudinal- 1y spaced scoop boot 73.

Again, it will be understood that the earth material contained in hopper 83 can be fed into the input kiln end 16 and mixed with the earth material fed from either one or both of. the hoppers 42 and 80 through their respective associated scoop boots 34 and 73.

The invention relates to the differentially preheating of two or more earth materials to different preheat temperatures, and the feeding of such dilferentially preheated earth materials simultaneously into the burner flame of a kiln for expansion. A horizontal or vertical kiln can be used. The preheating can be preformed by any suitable means, such as separate preheat tubes.

Although the invention has been described by making detailed reference to a single preferred embodiment, such detail is to be understood in an instructive, rather-than in any restrictive sense, many variants being possible.

I claim as mv invention:

1. An apparatus for expanding earth material, comprising:

(a) an elongate, expander kiln having an input end and an output end, the kiln including a plurality of substantially concentric tubes,

(b) adjacent tubes having a longitudinal feed passage therebetween,

(c) a burner directing a flame into the input end of the kiln, and longitudinally of the innermost tube, the flame heating the feed passage between adjacent tubes,

(d) a first feed means introducing an earth material into a feed passage at a first entrance spaced longitudinally from the input end of the kiln, the earth material being preheated in its movement through the feed passage from the first entrance to the input end of the kiln,

(e) a second feed means delivering earth material to the input end of the kiln at a ditferent temperature than that provided by the first feed means, and

(f) means collecting and delivering the earth materials into the burner flame at the input end of the kiln for expansion.

2. An apparatus for expanding earth material as defined in claim 1, in which:

(g) the second feed means introduces earth material to a feed passage at a second entrance spaced longitudinally from the first entrance in a direction toward the input end of the kiln, whereby the earth material incurs a lesser preheat from the burner flame in traveling through the feed passage than the earth material introduced by the first feed means.

3. An apparatus for expanding earth material comprising:

(a) an elongate, expander kiln having an input end and an output end, the kiln including a plurality of substantially concentric tubes,

(b) adjacent tubes having a longitudinal feed passage therebetween,

(c) a burner directing a flame into the input end of the kiln, and longitudinally of the innermost tube, the flame heating the feed passage between adjacent tubes,

(d) a first feed means introducing an earth material into a feed passage at a first entrance spaced longitudinally from the input end of the kiln, the earth material being preheated in its movement through the feed passage from the first entrance to the input end of the kiln,

(e) another feed means delivering earth material to the input end of the kiln without preheat from the burner flame, and

(f) means collecting and delivering the earth materials into the burner flame at the input end of the kiln for expansion.

4. An apparatus for expanding earth materials as defined in claim 1, in which:

(g) a longitudinal feed passage is provided between each adjacent pair of tubes, each feed passage being subjected to a greater preheat temperature from the burner flame than the next radially outward feed passage,

(h) the first feed means introduces earth materials into one feed passage, and

(i) the second feed means introduces earth material into another feed passage so as to subject the earth materials to different preheat temperatures.

5. An apparatus for expanding earth materials as defined in claim 1, in which:

(g) a longitudinal feed passage is provided between each adjacent pair of tubes, each feed passage being subjected to a greater preheat temperature from the burner flame than the next radially outward feed passage, and

(h) a bypass means is disposed between an adjacent pair of tubes to divert earth material selectively from one feed passage to another radially adjacent feed passage to change the preheat temperature to which the earth material is subjected.

6. An apparatus for expanding earth material as defined in claim 1, in which:

(g) a longitudinal feed passage is provided between each adjacent pair of tubes, each feed passage being subjected to a greater preheat temperature from the burner flame than the next radially outward feed passage,

(h) the first feed means introduces earth material into one feed passage to subject the earth material to a predetermined preheat temperature,

(i) the second feed means introduces earth material into another feed passage so as to subject the earth material to different predetermined preheat temperature, and

(j) a bypass means is disposed between an adjacent pair of tubes to divert the earth material selectively from one feed passage to another passage to mix the earth materials and to change the preheat temperature to which at least one earth material is subjected.

7. An apparatus for expanding earth material as defined in claim *6, in which:

(k) the second feed means introduces earth material into another feed passage at a second entrance spaced longitudinally from the first entrance, and

(l) the bypass means is located longitudinally between the first and second entrances.

8. An apparatus for expanding earth material as defined in claim 1, in which:

(g) the kiln includes an inner tube, an outer tube and an intermediate tube,

'(h) the inner and intermediate tubes provide a first feed passage therebetween,

(i) the intermediate and outer tubes provide a second feed passage therebetween, the second passage being subject to a lesser preheat temperature than the first passage from the burner flame inside the inner tube,

(j) the first feed means introduces earth material into the first passage at the first entrance, and

(k) the second feed means introduces earth material into the second passage at a second entrance spaced longitudinally from the first entrance in a direction toward the input end of the kiln, the earth materials in the passages being subjected to different periods of preheat temperatures and to different preheat temperatures in traveling to the input end of the kiln.

9. An apparatus for expanding earth material as defined in claim 8, in which:

(1) a bypass means is located at the intermediate tube for diverting earth material selectively from the first passage to the second passage to change the preheat temperature to which such earth material is subjected.

10. An apparatus for expanding earth material as defined in claim 8, in which:

(1) a third feed means introduces earth material directly to the input of the kiln without preheat from the burner flame.

11. An apparatus for expanding earth material as defined in claim 8, in which:

(1) the first entrance to the first passage is located adjacent the output end of the kiln,

(m) the second entrance to the second passage is located between the first entrance of the first passage and the input end of the kiln, and

(n) a bypass means is located at the intermediate tube and is located between the first and second entrances for selectively diverting earth material from the first passage to the second passage.

12. A method of expanding earth material comprising the steps of:

(a) moving earth material a predetermined distance longitudinally of an elongate kiln, and in heat exchange relation to the primary burner flame of such kiln,

(b) preheating the earth material with the burner flame during such movement,

() collecting the preheated earth material and delivering the earth material directly into the burner flame for expansion within the kiln,

(d) moving the earth material toward the burner flame during preheat at a predetermined radial distance from the primary burner flame,

(e) selectively moving the earth material radially outward from the first predetermined radial distance from the burner flame,

(f) moving the earth material longitudinally of the kiln toward the burner flame at the last said radial distance from and in heat exchange relation to the primary burner flame, and

(g) preheating the earth material with the burner flame during such movement at both radial distances at different preheat temperatures.

13. The method of expanding earth material comprising the steps of:

(a) moving earth material a predetermined distance longitudinally of an elongate kiln, and in heat exchange relation to the primary burner flame of such kiln,

(b) preheating the earth material with the burner flame during such movement,

(0) collecting the preheated earth material and delivering the earth material directly into the burner flame for expansion Within the kiln,

(d) moving a second earth material, a shorter predetermined distance than the first earth material, longitudinally of the kiln and in heat exchange relation to the primary burner flame,

(e) preheating the second earth material with the same burner flame during such movement, and

(f) collecting the preheated first and second earth materials and delivering both materials, together, direlctly into the burner flame for expansion in the kin.

14. The method of expanding earth material as defined in claim 13, comprising the further step of:

(g) moving the first and second earth materials selectively at diflerent radial distances from the burner flame to attain different preheat temperatures.

15. The method of expanding earth material as defined in claim 14, comprising the further step of:

(h) selectively diverting one of the earth materials at one radial distance from the burner flame to a different radial distance from the burner flame to change the preheat temperature subjected to such earth material.

16. The method of expanding earth material as defined in claim 14, comprising the further steps of:

(h) selectively diverting one of the earth materials at one radial distance from the burner flame to a diiferent radial distance from the burner flame to change the preheat temperature subjected to such earth material and to mix the first and second earth materials during preheat.

17. The method of expanding earth material comprising the steps of:

(a) moving earth material a predetermined distance longitudinally of an elongate kiln, and in heat exihlange relation to the primary burner flame of such (b) preheating the earth material with the burner flame during such movement,

(c) collecting the preheated earth material and delivering the earth material directly into the burner flame for expansion Within the kiln,

(d) introducing a second earth material directly to the input end of the kiln without preheating by the burner flame,

-(e) mixing the preheated first earth material with the second earth material at the input end, and

(f) collecting the mixture of the earth materials and delivering the mixture directly into the burner flame for expansion in the kiln.

18. A method of expanding earth material, comprising the steps of:

(a) passing one or more supplies of earth material longitudinally of an elongate kiln selectively at one or more predetermined radial distances from and in lllelalt exchange relation to the primary burner of the (b) moving each supply of earth material at any one of a plurality of predetermined longitudinal distances toward the input end of the kiln,

(c) preheating each supply of earth material at any one of a plurality of preheat temperatures from the burner flame during such movement toward the input end of the kiln depending upon the selected radial distance and selected longitudinal distance,

(d) collecting the preheated earth material at the input end of the kiln, and

(e) delivering the preheated earth material directly into the burner flame for expansion in the kiln.

19. An apparatus for expanding earth materials, comprising:

(a) an expander kiln including an inner tube and a concentric portion external to the inner tube,

(b) a burner directing a flame into the kiln,

(0) means preheating different supplies of earth ma- 1 1 terials to different preheat temperatures in the external portion, and

(d) means delivering the difierentially preheated earth materials simultaneously into the burner flame for expansion and discharge through the inner tube.

20. A method of expanding earth material, comprising the steps of:

(a) preheating different supplies of earth materials to different preheat temperatures in an outer preheating zone concentric to an inner discharge zone,

(b) delivering the differentially preheated earth materials simultaneously into a burner flame of a kiln for expansion, and

12 (c) discharging the expanded materials through the inner zone.

References Cited I UNITED STATES PATENTS 2,621,034 12/1952 Stecker. 2,633,346 3/1953 Stein.

JOHN J. CAMBY, Primary Examiner U.S. ci. 12. 

